1. Field of the Invention
The present invention relates to a solid-state imaging device, a driving method thereof, and an imaging apparatus. More particularly, the present invention relates to a solid-state imaging device capable of achieving a wide dynamic range, a driving method thereof, and an imaging apparatus using the solid-state imaging device capable of achieving a wide dynamic range.
2. Description of the Related Art
Recently, video cameras, still digital cameras, and other apparatuses using solid-state image sensors such as CCDs (charge coupled devices) have become popular.
FIG. 12 is a diagram illustrating a still-image exposure sequence of the related art. According to a driving method of a solid-state imaging device according to the related art, the still-image exposure sequence includes a high-speed imaging period (monitoring mode), an exposure period, a high-speed sweep period, and a frame readout period. The still-image exposure sequence transitions to another monitoring period after the frame readout period. In the still-image exposure sequence of the related art, electronic shutter signals φSUB are generated in the exposure period, and a period (which is denoted by a symbol E in the figure) that continues from the rising time of the last electronic shutter signal to the time when a mechanical shutter is closed corresponds to the exposure period.
However, when a subject is shot with a solid-state imaging device with a narrow dynamic range, “whiteout” or “blackout” occurs which is a phenomenon where gradation data in bright or dark areas are lost.
JP-A-8-084298 discloses a technique of achieving a wide dynamic range. Specifically, according to the technique, signal charges accumulated in a first group of photoelectric conversion elements are read out first, signal charges accumulated in a second group of photoelectric conversion elements are read out subsequently, and the respective signal charges are converted into signal outputs without combining them together.